Promotional Role of Surface Defects on Carbon-Supported Ruthenium-Based Catalysts in the Transfer Hydrogenation of Furfural

Article abstract of DOI:10.1002/cctc.201601070

The synthesis of highly efficient supported metal catalysts is of vital importance for the modern development of the production of chemicals. In this regard, biomass-based chemical transformation holds potential promise through many heterogeneous catalytic processes. Herein, we report surface defect engineering on a carbon-supported, Ru-based catalyst by a two-step hybridization–self-reduction route, which involves the assembly of a hybrid composite of ternary Co-Al-Ru layered double hydroxide (CoAlRu-LDH) and amorphous carbon through the carbonization of glucose and a subsequent in situ self-reduction process. The results revealed that Ru³⁺ species in the resulting CoAlRu-LDH-C composite could be reduced in situ to Ru⁰ species by the carbon component in the hybrid composite, and Co-containing spinels with a large quantity of surface oxygen vacancies could be formed simultaneously on the surface. The as-fabricated Ru-based catalyst showed a superior catalytic performance in the liquid-phase transfer hydrogenation of furfural to furfuryl alcohol using benzyl alcohol as hydrogen donator to other Ru-based catalysts derived from LDH-C composite precursors. It was proven that surface defects (i.e., oxygen vacancies, Co²⁺ species) could enable the chemisorption of furfural spatially and ensure the activation of its carbonyl groups, which promoted the transfer hydrogenation greatly.

Full text of DOI:10.1002/cctc.201601070

Accepted Article
Title: Promotional role of surface defects on carbon-supported Ru-
based catalysts in transfer hydrogenation of furfural
Authors: Zhi Gao, Lan Yang, Guoli Fan, and Feng Li
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10.1002/cctc.201601070
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Promotional role of surface defects on carbon-supported
Ru-based catalysts in transfer hydrogenation of furfural
Zhi Gao, Lan Yang, Guoli Fan and Feng Li*
Abstract: The synthesis of highly efficient supported
metal catalysts is of vital importance for the modern
development of the production of chemicals. In this
regard, biomass-based chemical transformation holds
potential promise through many heterogeneous catalytic
processes. Herein, we report surface defect engineering
on carbon-supported Ru-based catalyst via a two-step
hybridization-self reduction route, which involves the
assembly of hybrid composite of ternary Co-Al-Ru
layered double hydroxide (CoAlRu-LDH) and amorphous
carbon through the carbonization of glucose and
following an in situ self-reduction process. The results
revealed that Ru3+ species in the resulting CoAlRu-LDH-
C composite could be in situ reduced to Ru0 species by
the carbon component in the hybrid composite, and Co-
containing spinels with a large quantity of surface oxygen
vacancies could be simultaneously formed on the surface.
As-fabricated Ru-based catalyst was found to show a
superior catalytic performance in the liquid phase transfer
hydrogenation of furfural to furfuryl alcohol using benzyl
alcohol as hydrogen donator to other Ru-based ones
derived from LDH-C composite precursors. It was proven
that surface defects (i.e. oxygen vacancies, Co2+ species)
could enable spatially the chemisorption of furfural and
ensure the activation of carbonyl groups in furfural,
thereby greatly promoting the transfer hydrogenation.
However, the use of molecular hydrogen usually produced
from coal and other natural gas may bring out several
problems related to hydrogen availability, high cost, and
safety issues.[16,17] Recently, it was reported that FA was
selectively converted to FOL through liquid-phase transfer
hydrogenation using different alcohols as hydrogen donors
in the presence of catalysts,[18-20] which avoided the use of
gaseous molecular hydrogen and thus reduced the
production costs for practical applications.[21] Moreover,
non-corrosive alcohols can be sustainably obtained from
biomass resources, while useful dehydrogenation products
(i.e. aldehydes or ketones) may be easily separated.[22-24]
Therefore, compared with conventional hydrogenation
process, transfer hydrogenation using organic hydrogen
donators should be a greener alternative. In most cases,
however, it is difficult to achieve high yields of products in
the hydrogen transfer process because of low efficiency of
catalysts. In this regard, designing highly efficient
heterogeneous catalysts is quite crucial for the production
of FOL through the transfer hydrogenation of FA on an
industrial scale.
Introduction
Nowadays, with both the shortage of fossil resources and
the increasing greenhouse gas emission on a global scale,
developing chemical manufacturing through the conversion
of sustainable raw biomass, which can replace
conventional fossil-based production process, is attracting
numerous attentions in modern industry.[1-3] For example, a
wide range of important chemicals including furfural (FA),
5-hydroxymethyl furfural, sorbitol and levulinic acid can be
obtained from agricultural waste resources. As one of the
most important biomass-derived platform molecules, FA is
widely converted to a great number of useful and high
added value chemicals through
a series of complex
reaction networks.[4,5] Among a variety of its derivative
products, furfuryl alcohol (FOL) is one of the most valuable
compounds, because it can be utilized to produce various
chemicals including synthetic fibers, resins, foundry binders,
adhesives and fine chemicals.[4-6] Commonly, FOL is
produced by hydrogenating FA using heterogeneous
metal-based (i.e. Pd, Ru, Pt, Cu) catalysts supported on
carbon, alumina or silica.[7-13] Although noble metal-based
catalysts exhibited excellent activity, several secondary
reactions such as hydrogenolysis of C-O bond,
decarbonylation of FA and hydrogenation of furan ring, as
well as the formation of condensation byproducts, also
often occured.[14,15] Therefore, the quite high yield of FOL
still is not easily obtained. As for non noble metal-based
catalysts, lower catalytic activity is main disadvantage.
Generally, liquid-phase selective hydrogenation of FA
to FOL is conducted under high hydrogen partial pressure.
On the other hand, it is well known that the geometric
and electronic effect of metal species in supported metal
catalysts can significantly influence their hydrogenation
activities and selectivities.[25] As for hydrogenation
reactions, reducible oxide supports (i.e. TiO2 and MoO3)
have been widely used to enhance the activity of
catalysts,[26,27] since surface oxygen vacancies on these
oxide supports were thought to be able to strongly interact
with
reactant
molecules.[28-31]
Unfortunately,
the
development of biomass-based organic synthesis based on
these oxide materials was scarcely reported. To enable the
chemisorption and activation of reactant molecules, surface
structures on the catalysts should be certainly better
engineered, so as to create defect states and form close
heterojunctions, which are good for achieving the
enhanced catalytic efficiency.
Z. Gao, Prof. L. Yang, Dr. G. Fan, Prof. F. Li
State Key Laboratory of Chemical Resource Engineering
Beijing University of Chemical Technology
P. O. BOX 98, Beijing, 100029, P. R. China.
E-mail: lifeng@mail.buct.edu.cn; Fax: +8610-64425385;
Tel.: +8610-64451226
As a class of highly ordered two-dimensional layered
clay materials,[32-34] Layered double hydroxides (LDHs) with
the general formula [M1−x2+Mx3+(OH)2]x+[Ax/n
]
n−⋅mH2O are
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/cctc.xxxxx.
1
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10.1002/cctc.201601070
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applied widely as catalyst precursors due to their structural
versatility and flexibility achieved by varying divalent or
trivalent metal cations either on the layers or in the
interlayer metal complex anions. Especially, highly
dispersed and stable metal nanoparticles (NPs) can be
generated by the structural topotactic transformation of
LDH precursors with desired metal species upon
calcination under a reductive atmosphere. Currently, we
have explored the generation and stabilization of highly
dispersed supported Ni or Pd NPs via the reduction of
composites of LDH containing Ni2+ cation or interlayer
mainly attributable to the dilution effect of the carbon
component, as well as the reduced crystallinity of LDH
phase in the composite.
Figure 1B shows the XRD patterns of different carbon-
supported Ru-based samples. Co-Ru/C, Ni-Ru/C, Mg-Ru/C
and Zn-Ru/C present broad and weak diffractions of
crystalline Co-containing spinel (i.e. Co3O4, CoAl2O4), NiO,
MgO and ZnO phases,[38] respectively, owing to the
structural collapse of LDH phase after calcination and
following reduction process. The poor crystallinity is
associated with the small particle size of resulting oxides.
Simultaneously, in each case, no diffractions related to
metallic Ru0 phase are found, due to the quite low Ru
contents, probably as well as the presence of highly
dispersed Ru NPs.
2-
PdCl4 anion and amorphous carbon upon heating under
inert atmosphere.[25,35]
Inspired by previous pioneering works, herein, we
reported surface defect engineering on a new carbon-
supported Ru-based nanocatalyst via
a
two-step
hybridization-self reduction route, which involved the
assembly of hybrid composite of ternary CoAlRu-LDH and
amorphous carbon through the carbonization of glucose
and following an in situ self-reduction process. The carbon
in the CoAlRu-LDH-C hybrid composite serving as a
reducing agent could in situ reduce Ru3+ species to form
metallic Ru0 NPs under N2 atmosphere, while Co-
containing spinels with a large quantity of surface oxygen
vacancies could be simultaneously formed on the surface.
The resulting Co-Ru/C nanocatalyst was employed as a
heterogeneous catalyst for liquid phase transfer
hydrogenation of FA to produce FOL using benzyl alcohol
as hydrogen donor. Our results demonstrated that as-
fabricated Co-Ru/C nanocatalyst presented a significantly
enhanced catalytic performance with a 100 % selectivity to
FOL at almost complete FA conversion. High catalytic
efficiency could be mainly attributable
Figure 1. XRD patterns (A) of LDH-C precursors: (a) CoAlRu-LDH-
C, (b) MgAlRu-LDH-C, (c) NiAlRu-LDH-C, and (d) ZnAlRu-LDH-C,
and XRD patterns (B) of Co-Ru/C (a), Mg-Ru/C (b), Ni-Ru/C (c),
and Zn-Ru/C (d). The inset in (A) shows XRD patterns of pure
CoAlRu-LDH sample.
to the promotional effect of surface defects (i.e. oxygen
vacancies, Co2+ species,) by ensuring the chemisorption
and activation of carbonyl group in FA molecule, thereby
greatly lower the energy requirement for the transfer
hydrogenation. Profiting from the activation of carbonyl
groups on surface defects, such Co-Ru/C catalyst could be
Under the present hydrothermal conditions for the
synthesis of various LDH-C composites, the aromatization
and carbonization of glucose can occur, thus leading to the
generation of amorphous carbon. Further, Ru-containing
LDH crystallites obtained could be assembled with the
resultant carbon to form LDH-C hybrid composites.
Subsequently, Ru3+ species in LDH-C samples were
reduced to form carbon-supported oxide-modified Ru-
based samples. The physical properties and compositions
of supported samples are presented in Table 1. In each
case, element analysis by ICP-AES gives a Ru loading of
3.2-3.6 wt.%, in good agreement with the theoretical value.
The BET surface area of Ni-Ru/C sample determined by
nitrogen sorption measurements reaches as high as 313
m2 g−1, which is higher than other samples. However, Co-
Ru/C possesses a much lower specific surface area of 98
m2 g−1, owing to the formation of spinel phases in sample.
As shown in Figure 2a, TEM image of representative
Co-Ru/C sample reveals that a great quantity of small NPs
with the particle size of about 5.4 nm are well-dispersed on
the carbon support. Further, a typical HRTEM image shows
that two adjacent NPs possess clear lattice fringes with the
extended to
a wide range of transfer hydrogenation
processes of biomass-derived carbonyl compounds. More
importantly, the defect-rich catalyst exhibited high stability
in multiple successive runs and well remained the high
catalytic activity.
Results and Discussion
Structural analysis of catalysts
Figure 1A shows the XRD patterns of different LDH-C
hybrid composite precursors. It is clear that XRD patterns
of LDH-C samples exhibit the typical characteristic
diffractions indexed to (003) (006), (012), (015), (018), (110)
and (113) crystalline planes of hydrotalcite-like materials.[36]
The (003) plane at 2θ=11.6° arises from the basal spacings
of approximately 0.76 nm, well consistent with that for
carbonate-intercalated hydrotalcite.[37] Moreover, the
absence of the diffractions related to graphite or other
forms of carbon phases confirms the presence of
noncrystalline carbon in LDH-C samples. Specially,
compared with pristine CoAlRu-LDH, CoAlRu-LDH-C
hybrid composite presents broader and weaker diffractions,
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10.1002/cctc.201601070
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interplanar spacings of about 2.34 Å and 4.67 Å (Figure 2b),
metallic Ru phase and (111) plane of Co3O4 spinel phase.
Meanwhile, the intimate interfaces between spinel and
metallic Ru account for the strong interaction between
them. And, the uniform distributions of Ru, Co, Al and C
elements can be found according to the EDS mapping from
HAADF-STEM image (Figure 2c,d), while the STEM-EDX
line scan spectra confirm the relative distributions of Ru,
Co and Al elements with two adjacent particles (Figure
2e,f). It is clear that Ru, Co and Al lines show a similar
respectively, which can be indexed to the (100) plane for
distribution along two particles in spite of a weaker signal
for Ru element, reflecting the character of their close
contact. In addition, TEM images of other supported Ni-
Ru/C, Zn-Ru/C and Mg-Ru/C samples and particle size
distribution histograms of Ru NPs estimated based on TEM
images are shown in Figure S1. In all cases, black Ru NPs
also are well dispersed on the support and undergo no
agglomeration with the average sizes of about 2.9 nm for
Ni-Ru/C, 4.4 nm for Zn-Ru/C and 3.6 nm for Mg-Ru/C.
Table 1. The compositions, textual and structural properties of different samples.
[d]
[e]
[f]
[g]
[h]
Samples
Ru [a]
(wt.%)
3.4
Co [a]
(wt.%)
35.2
Zn [a]
(wt.%)
-
Ni [a]
(wt.%)
-
Mg [a]
C [b]
Dis [c]
(%)
SBET
Dpore
Vpore
Nv
DRu
(wt.%) (wt.%)
(m2 g-1)
(nm)
22.8
(cm3 g-1) (μmol g-1)
(nm)
5.4
Co-Ru/C
Zn-Ru/C
-
-
40.9
41.3
20.1
98
0.62
0.35
198.5
32.7
3.2
-
35.8
-
23.0
269
26.7
4.4
Ni-Ru/C
3.3
3.6
-
-
-
-
34.5
-
-
39.7
48.3
48.9
34.7
313
278
8.6
0.39
0.44
22.8
11.2
2.9
3.6
Mg-Ru/C
25.2
23.7
[a] Determined by ICP-AES.[b] Determined by elemental analysis. [c] Dispersion degree of Ru determined by H2-TPD. [d] BET surface area.
[e] Average pore size. [f] Total pore volume. [g] Determined by the oxygen pulse injection method; [h] Average size of Ru NPs calculated by
TEM analysis.
reduced Co-Ru/C and Co/C (Figure 3). For reduced Co/C
sample, first small peak at about 405 °C is assigned to the
reduction of surface Co3+ species; the second peak at
about 541 °C represents the reduction of Co3+ to Co2+
species in the bulk phase; the third peak at about 643 °C is
associated with the further reduction of Co2+ to Co0
species.[39] In the case of Co-Ru/C sample, a small peak at
about 150 °C is ascribed to the further reduction of cationic
Ru species.[40,41] It is interesting to note that with the
addition of Ru, the reduction of Co species shifts to lower
temperatures, presumably due to the hydrogen spillover
from the reduced Ru, thereby easily reducing cobalt oxide
species.[42,43] In addition, another small reduction at 662 °C
is associated with the reduction of large cobalt-containing
spinel particles. Further, as for the reduction of Co species,
an increase in the amount of H2 consumption in H2-TPR
from 5.21 mmol g-1 for Co-Ru/C to 6.74 mmol g-1 for Co/C
reveals the presence of more Co2+ species in the Co-Ru/C.
The above results further confirm the presence of strong
interactions between Co and Ru species in the Co-Ru/C
sample.
Figure 2. HRTEM images (a, b) of Co-Ru/C sample. HAADF-
STEM image (c and e) of Co-Ru/C with the EDX mapping of Co-K,
Al-K, C-K and Ru-K (d); EDX line scan spectra of Co-K, Al-K and
Ru-K along the red line in e (f). The inset in (a) shows the particle
size distribution of Ru NPs.
Redox behaviors and surface properties of
catalysts
In order to gain insight into the metal-support interactions in
Figure 3. H2-TPR profiles of reduced Co/C (a) and Co-Ru/C (b)
samples, H2-TPR experiments were also conducted over
samples.
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To investigate the surface electronic structure of Co, Ru
and O species in Ru-based samples, XPS measurements
were carried out. Figure 4 shows the fine spectra of Co 2p
core levels for Co-Ru/C and Co/C samples. In addition to a
weak shake-up satellite at about 786.3 eV, an
asymmetrical Co 2p 3/2 XPS peak at about 781.0 eV can
be deconvoluted into two components at binding energy
(BE) of about 779.8-780.2 and 781.5-782.0 eV,
respectively, which are assignable to surface Co3+ and
Co2+ species in the form of Co-containing spinel phases.[44]
It is noticeable that after the loading of Ru NPs, the
intensity ratio of Co2+ to Co3+ species is dramatically
increased from 1.3 to 4.3 (Table 2). It suggests the
formation of more Co2+-containing spinels in the as-
fabricated Co-Ru/C sample, because of the reduction of
more Co3+ to Co2+ species during the in situ self-reduction
of Ru3+ species. On the other side, the increase in the
proportion of surface Co2+ species also means the
formation of more surface oxygen vacancies (Ov) in the
form of Co2+–Ov–Co2+ structures in the sample.[45]
of Co3+ species in the structure of spinel by the carbon
component in the hybrid CoAlRu-LDH-C may lead to the
loss of the lattice oxygen and thus the formation of oxygen
vacancies according to the following equation: Co3+–O2-–
Co3+ + C→ Co 2+–Ov–Co2+ + CO. Accordingly, the higher
surface Co2+/Co3+ ratio should be related to the higher
amount of defect structures (i.e. Co2+ species, surface
oxygen vacancies) in the Co-Ru/C sample.
Figure 5. XPS of O 1s region for different samples.
For Co-Ru/C sample, one broad peak at about 281.0
eV in the fine spectrum of Ru 3d region is assigned to the
spin–orbit component for Ru 3d 5/2 core level (Figure 6).
Further, the broad Ru 3d 5/2 peak may be deconvoluted
into two components at about 280 and 281 eV (inset in
Figure 6), respectively, which are characteristic of metallic
Ru0 species and cationic Ruδ+ species. Such cationic Ruδ+
species may be formed through the strong interaction of
Ru species with the adjacent metal oxide support, thus
leading to the occurrence of charge transfer.[48] As listed in
Table 2, one can find that the proportion of Ruδ+ species in
the total Ru species increases gradually in the following
order of Zn-Ru/C < Mg-Ru/C < Ni-Ru/C < Co-Ru/C.
Figure 4. XPS of Co 2p region for Co/C and Co-Ru/C samples.
As shown in Figure 5, there are three fitted peaks in the
spectra of O1s region for supported Ru samples,
corresponding to three different kinds of surface oxygen
species. The peak (OI) at lower BE of 530.2 eV is mainly
ascribable to the lattice oxygen species in the spinel
structure; the peak (OII) at about 531.7 eV is ascribable to
surface oxygen species (e.g., O2 , O2 or O-) adsorbed on
surface oxygen vacancies belonging to defect-oxide, as
well as hydroxyl-like groups adsorbed on metal ions; the
peak (OIII) at 533.1 eV belongs most likely to the mixture of
adsorbed water and CO2 on the surface.[46,47] It is noted
from Table 2 that compared with that for Co/C, the intensity
ratio of OII to OI species used to estimate qualitatively the
relative amount of surface defects (i.e. oxygen vacancies)
is greatly increased after the loading of Ru NPs, well
consistent with its higher surface Co2+/Co3+ ratio. Further,
OSC measurements were carried out to quantitatively
determine the concentration of surface oxygen vacancies
on supported Ru-based samples. As shown in Table 1,
compared with other supported ones, Co-Ru/C sample
possesses a much higher value of oxygen vacancies
(198.5 μmol g-1), in good accordance with the above O 1s
XPS results. In the case of Co-Ru/C sample, the reduction
-
2-
Figure 6. XPS of Ru 3d region for different samples. The inset
shows the detail spectra of Ru 3d region in the range of 278.5–
282.7 eV.
4
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Table 2. Surface chemical states of Co, O and Ru species on different samples.
+
+
Samples
Surface Co2+/Co3+
molar ratio [a]
Surface OII/OI
molar ratio [b]
Surface Ruδ / (Ru0+Ruδ
)
molar ratio [c]
Co/C
1.3
4.3
--
1.30
1.90
0.84
1.11
0.71
--
Co-Ru/C
Ni-Ru/C
Zn-Ru/C
Mg-Ru/C
0.49
0.44
0
--
--
0.27
[a] Determined by XPS of Co 2p region. [b] Determined by XPS of O 1s region. [c] Determined by XPS of Ru 3d 5/2 region.
Moreover, Co-Ru comparison sample without
amorphous carbon was characterized by XPS. Clearly,
there is only a peak at about 281.4 eV in the Ru 3d 5/2
region (Figure S2), indicative of the character of RuO2. It
further demonstrates that amorphous carbon in LDH-C
precursors can in situ reduce Ru species, and strong
interactions between Ru species and adjacent metal oxide
supports contribute to the presence of Ruδ+ species in
reduced samples.
after 12 h. 100% FOL yield can be achieved in four
different catalysts after 26 h. Although the surface area of
Co-Ru/C catalyst is much lower than those of other
supported Ru-based ones, it shows the best catalytic
behavior. It demonstrates that the surface area is not a key
factor for governing the catalytic performance in the
present carbon-supported Ru-based catalyst system.
Moreover, compared with previously reported catalysts
(Table S1),[55-57] Co-Ru/C catalyst exhibits comparable or
higher catalytic performance for the transfer hydrogenation
of FA, in spite of different reaction conditions.
Since Raman spectroscopy is very sensitive to both
Co–O bond arrangement and lattice defects, Raman
analysis of Co/C and Co-Ru/C samples was performed. As
shown in Figure S3, Co/C and Co-Ru/C samples show five
On the other hand, in the heterogeneous catalytic
system, the highly dispersed metal NPs always possess
more assessable catalytically active sites. It is well-
documented that hydrogen donors can be dissociatively
chemisorbed over metal particles to generate active
hydrogen atoms, and hydrogen is further transferred to
reactant molecules.[58-60] However, compared with other
catalysts, Co-Ru/C with lower dispersion and reduction
degree of Ru species possesses a smaller amount of
accessible active Ru0, which is disadvantageous to the
dehydrogenation of benzyl alcohol and thus the hydrogen
transfer for the hydrogenation of carbonyl group in FA. The
above results reflect that the dispersion nature of active
metal species also cannot explain the change in the
catalytic performances of catalysts.
characteristic Raman peaks at 191, 481, 524, 617 and 688
cm−1, respectively, which correspond to the F2g(1), Eg, F2g
,
(2)
F2g and A1g symmetry of Co3O4 phase.[49-51] Compared
with those for Co/C, five Raman peaks for Co-Ru/C sample
all shift to lower frequencies and are broadened, indicative
of the lattice distortion.[52,53] It is well established that the
incorporation of Co2+ ions having smaller ionic radii can
induce the shifting of neighboring O atoms towards Co2+ in
the structure of Co3O4 spinel. Consequently, the induced
oxygen distortion can enhance the lattice strain that will be
relaxed by the formation of an oxygen vacancy in the
vicinity of the Co2+. As a result, such lattice strain of Co-
containing spinel further confirms the presence of more
oxygen vacancies and Co2+ species in the Co-Ru/C sample.
(3)
Catalytic transfer hydrogenation of FA
The catalytic performance of various catalysts was
tested for the catalytic transfer hydrogenation of FA to
produce FOL using benzyl alcohol as both the hydrogen
donor and the solvent. The transport limitations for the
catalytic transfer hydrogenation of FA were examined by
Madon–Boudart method,[54] where the rates of FOL
production were measured on three Co-Ru/C samples with
different Ru loadings at 150 °C and 170 °C. As shown in
Figure S4, the ratios of the measured reaction rate equal
the ratios of the concentration of surface Ru atoms at
150°C and 170 °C, indicating the absence of transport
limitations in the reaction. For Zn-Ru/C, Ni-Ru/C and Mg-
Ru/C catalysts, the same results are also obtained.
As shown in Figure 7, different Ru-based catalysts
exhibit remarkable differences in the catalytic transfer
hydrogenation performance at 150 °C. In each case, the
selectivity to FOL almost remains 100 % with reaction time.
Co-Ru/C catalyst yields a high FOL yield of 98 % after 12 h.
However, much lower FOL yields were obtained over Zn-
Ru/C (69.9 %), Ni-Ru/C (81.1 %) and Mg-Ru/C (71.4 %)
Figure 7. Catalytic performance of different Ru-based catalysts in
the transfer hydrogenation of FA. Reaction conditions: FA, 3.6
mmol; catalyst, 0.1 g; reaction temperature, 150 °C; benzyl alcohol,
10 ml.
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In order to gain more information on the surface-
bonding state for FA adsorbed on catalysts, in situ FT-IR
characterization of FA adsorbed on Ru-based catalysts
was conducted. As shown in Figure 8, in each case, the in
situ FT-IR spectrum in the range of 1600-1800 cm-1
presents a weak vibration at about 1721 cm-1 and a
relatively strong vibration at about 1671 cm-1. The
adsorption at higher frequency should be assigned to the
stretching vibration of the C=O bond in physisorbed
alpha,beta-unsaturated aldehydes (e.g. FA) based on the
NIST database,[61] while the adsorption at lower frequency
is assocaited with a weakening of the C=O bond,[62] due to
the interaction of carbonyl group with the catalyst surface.
It is interesting to note that the vibration intensity of the
C=O bond at 1671 cm-1 increases progressively in the
order of Zn-Ru/C < Mg-Ru/C < Ni-Ru/C < Co-Ru/C,
reflecting the improved adsorption capacity for FA
molecules. The result is in good agreement with their
catalytic performances in the transfer hydrogenation of FA
(See Figure 7).
some extent.
Further, in order to gain the intrinsic nature of
catalytically active Ru sites, the initial turnover frequency
(TOF) was calculated based on the moles of FOL produced
per mole surface metallic Ru in the 2 h. As showed in
Figure 9, the initial TOF value over the Ni-Ru/C (51.7 h-1) is
much lower than that over the Co-Ru/C (173.8 h-1) with a
larger amount of surface oxygen vacancies (198.5 μmol g-
1), although the amount of surface Ruδ+ species on the Ni-
Ru/C is the same as that on the Co-Ru/C. Moreover, the
TOF value over the Zn-Ru/C with more surface oxygen
vacancies (32.7 μmol g-1) and without surface Ruδ+ species
is almost the same as that over the Ni-Ru/C with more Ruδ+
species and less oxygen vacancies (22.8 μmol g-1), and
higher than that over the Mg-Ru/C with less oxygen
vacancies (11.2 μmol g-1). The aforementioned results
demonstrate that surface oxygen vacancies play a crucial
role in the transfer hydrogenation of FA.
Figure 9. Initial TOF values and amount of surface oxygen
Figure 8. In situ FT-IR of FA adsorbed on different catalysts at
vacancies (Nv) over different supported Ru catalysts.
30 °C.
Table 3. Initial reaction rate and apparent activation
In the present supported Ru-based catalyst system, like
metal ions (Ti3+ or Ce3+ species)/oxygen vacancies in the
TiO2 or CeO2 supported catalysts for the hydrogenation of
carbonyl group-containing compounds using molecular
hydrogen reported in the literature,[27,63,64] Co2+ species
adjacent to surface oxygen vacancies on the Co-Ru/C can
fix carbonyl groups in FA molecule, probably greatly
promoting the chemical adsorption of FA. Such interaction
between the reactant molecules and surface defects can
weaken the C=O, thereby facilitating the cleavage of
carbon-oxygen bond and hydrogenation. On the other side,
Vlachos et al. reported that the presence of surface Lewis
acid sites could promote the transfer hydrogenation of
FA.[55] Therefore, Py-IR analysis was performed to
determine surface acidity of different supported Ru-based
samples. In addition to the bands for the physical
adsorption of pyridine at 1436 cm-1 and 1587 cm-1 (Figure
S5), no observable characteristic bands from pyridine
energies
over different catalysts in the transfer
hydrogenation of FA.
Catalysts
Co-Ru/C
Ni-Ru/C
Zn-Ru/C
Mg-Ru/C
Initial reaction rate [a] (µmol gcat-1 s-1) Ea (kJ mol-1)
1.67
1.28
1.04
0.94
58
67
69
77
[a] Defined as the mole number of FOL produced per gram of
catalyst per second within the initial 2 h at 150 oC.
Furthermore, according to the fact that -ln(1-x) (x: FA
conversion) linearly increases with the reaction time over
o
different Ru-based catalysts at 110 oC, 130 oC and 150 C
(Figure S6), the transfer hydrogenation of FA shows first-
order kinetics due to large excess of benzyl alcohol. Based
on the calculated reaction rate constants (k) at different
temperatures (Figure 10), Co-Ru/C catalyst yields a lowest
apparent activation energy (Ea) of about 58 KJ/mol (Table
3), which is calculated from Arrhenius plots. The above
reaction kinetics results futher indicate the promotional
effect of surface defects on the transfer hydrogenation of
FA.
adsorption on acidic sites are observed in all cases,[65,66]
.
Therefore, the influence of surface acidity of supported Ru-
based catalysts on the transfer hydrogenation may be
excluded. However, surface electrophilic Ruδ+ species,
which are similar to electron-deficient cationic metal
species (e.g. Cu2+ or Cu+),[67-69] may interact with the C=O
bond through the lone pair electrons on the oxygen atom,
probably promoting the adsorption of substrate molecule to
6
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10.1002/cctc.201601070
ChemCatChem
FULL PAPER
Such configuration between FA and surface defects
significantly facilitated the chemisorption of FA, which could
spatially construct a channel for the electron transfer for the
activation of carbonyl groups, thus reducing dramatically
the barrier for FA hydrogenation. At last, Ru0 species can
facilitate the dehydrogenation of benzyl alcohol and
subsequently transfer active H atoms for the hydrogenation
of FA. In addition, in a way, surface Ruδ+ species may
facilitate the adsorption/activation of the C=O bond in FA
and the hydrogenation. Profitting from the spatial locations,
FA can easily react with benzyl alcohol to complete the
whole process. As
a result, surface defects provide
synergistic sites for adsorbing FA molecules and activating
carbonyl groups, coupling the hydrogen transfer through
Ru0 species. This control the key to the overall
dehydrogenation-hydrogenation coupling reaction.
The influence of different hydrogen donors on the
catalytic performance in the transfer hydrogenation of FA
was also investigated. It is found from Table 4 that Co-
Ru/C catalyst also yields a selectivity to FOL of 100% using
other hydrogen donors, such as primary alcohols (ethanol
and 1-butanol) and secondary alcohols (2-propanol, 2-
butanol and cyclohexanol), desipte the difference in the FA
conversion. It demonstrates that the selectivity purely
related to the applied catalytic systems cannot be affected
by the nature of hydrogen donors.
Figure 10. Ln (reaction rate constant) vs. reciprocal of reaction
temperature over different Ru-based catalysts in the transfer
hydrogenation of FA.
Further, the electronic states of O and Co species in
Co-Ru/C catalyst after the adsorption of FA were analyzed
by XPS (Figure S7). Clearly, compared with that before the
adsorption, the proportion of the OII species is reduced,
which is attributable to the strong bond between carbonyl
group in the FA and surface oxygen vacancies. In addition,
the proportion of Co3+ species is significantly increased
after the adsorption of FA (surface Co2+/Co3+ molar ratio
=1.44), due to charge transfer from the oxygen atom of
carbonyl group to Co2+ species.
Table 4. Catalytic transfer hydrogenation of FA using
different hydrogen donors. [a]
Hydrogen donor
Conversion
(%)
Selectivity
(%)
Yield
(%)
ethanol
1-butanol
43.7
32.4
100
100
100
100
100
100
43.7
32.4
100
According to the above characterization and
experimental results, a plausible mechanism for the liquid-
phase transfer hydrogenation of FA is proposed (Scheme
1). In the case of Co-Ru/C, Co2+ species adjacent to
oxygen vacancies can interact with the FA molecule
through bounding to the O atom of C=O bond to weaken
the carbonyl group. Correspondingly, C=O group can
oxidize Co2+ to Co3+ species, thus resulting in the formation
of C−O σ bond. Subsequently, the O atom of C−O σ bond
in FA can fill into the oxygen vacancy initially linked to Co2+.
2-propanol
2-butanol
100
100
cyclohexanol
52.8
52.8
[a] Reaction conditions: Co-Ru/C catalyst, 0.1 g; FA, 3.6 mmol;
solvent, 10 mL; reaction time, 4 h; reaction temperature, 150 °C;
N2 atmosphere.
Scheme 1 Proposed possible mechanism for the transfer hydrogenation of FA over as-fabricated Co-Ru/C catalyst.
7
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FULL PAPER
Reusability is one of the most attractive hallmarks of
catalysts, because a promising catalyst must exhibit fairly
stable catalytic performance in multiple successive runs.
The stability of the Co-Ru/C, Ni-Ru/C, Mg-Ru/C and Zn-
Ru/C catalysts were investigated at 150 °C for 6 h (Figure
11). After each recycling experiment, the used catalysts
were separated by filtration, dried at 70 °C for 12 h, and
reused in the next reaction. It is noted that the FOL yield
decreases only by about 3.5% after four consecutive runs
in Co-Ru/C, but for Ni-Ru/C, Mg-Ru/C and Zn-Ru/C
catalysts, the FOL yield decreases by as high as 21.6 %,
in Co-Ru/C is about 0.57 %, indicating a negligible leaching
of Ru species. Moreover, TEM images reveal the invariable
morphology of Co-Ru/C catalyst with little agglomeration of
41.7 % and 14.2 %, respectively. Interestingly, we note that
the stability of supported catalysts is in accordance with the
amount of surface oxygen vacancies on catalysts.
Especially, Co-Ru/C catalyst could well remain its oxygen
vacancies (192.1 μmol g-1) after 4 catalytic cycles. It implies
that surface oxygen vacancies can stabilize active metal
species because of strong metal–support interaction,
thereby improving the stability of catalysts. Elemental
analysis for the concentration of ruthenium in the solution
after four consecutive cycles by ICP-AES reveals that the
amount of ruthenium in solution relative to total ruthenium
Ru NPs after four cycles (Figure S8). The aforementioned
results reflect the excellent stability and reusability of the
Co-Ru/C catalyst.
Table 5. Hydrogenation of different carbonyl compounds over the Co-Ru/C catalyst. [a]
Entry
substrates
products
Conversion (%)
Selectivity (%)
100
1
93.4
2
3
90.7
97.8
95.8
100
4
5
95.1
85.9
94.2
100
6
7
97.3
96.8
98.5
100
8
9
96.5
98.5
100
100
[a] Reaction conditions: catalyst, 0.1 g; substrate, 3.6 mmol; benzyl alcohol, 10 mL; reaction time, 10 h; reaction
temperature, 150 °C; N2 atmosphere.
8
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10.1002/cctc.201601070
ChemCatChem
Co(NO3)2⋅6H2O,
Zn(NO3)2⋅6H2O,
Al(NO3)3⋅9H2O,
Ni(NO3)2⋅6H2O,
Mg(NO3)2⋅6H2O and RuCl3⋅3H2O were
purchased from J&K Scientific Ltd.. Na2CO3, NaOH and
glucose were purchased from Beijing Chemical Reagent
Company. All these chemicals were used as received.
Preparation of catalysts
CoAlRu-LDH precursor was synthesized by separate
nucleation and aging steps method reported by our group.[36]
Salt solution: Co(NO3)2⋅6H2O, Al(NO3)3⋅9H2O and RuCl3⋅3H2O
with the Co/Al/Ru molar ratio of 2:1:0.15 were dissolved in
deionized water. Base solution: Na2CO3 and NaOH ([CO32−] =
2[Al3+]; [OH−] = 1.6([Co2+] + [Al3+])) were dissolved in deionized
water (100 mL). The above two solutions were simultaneously
added to a colloid mill, mixed rapidly with the rotor speed of
3000 rpm for 2 min, and aged at 70 °C for 12 h. The resulting
suspension was centrifuged and washed with deionized water
until pH = 7.0. Subsequently, the as-obtained CoAlRu-LDH
was transferred into a Teflon-lined autoclave with 70 mL of
glucose solution ([C6H12O6] = 2.5([Co2+] + [Al3+])) and aged at
150 °C for 12 h. The suspension was centrifuged and washed
several times with deionized water, and then dried at 70 °C for
12 h. Subsequently, the as-obtained CoAlRu-LDH-C composite
was heated to 600 °C at a ramping rate of 5 °C min-1 under N2
atmosphere and held for 3 h. At last, when the temperature
was cooled to room temperature in N2 atmosphere, black Co-
Ru/C sample was rapidly sealed into a sample tube filled with
nitrogen to further perform characterization and catalytic
reactions. In addition, CoAl-LDH-C and its reduced Co/C
sample were also prepared according to the above identical
procedure without the addition of RuCl3⋅3H2O.
Figure 11. The reusability of diferent supported catalysts in the
transfer hydrogenation of FA. Reaction conditions: catalyst, 0.1 g;
FA, 0.3 mL; benzyl alcohol, 10 mL; reaction time, 6 h; reaction
temperature, 150 °C; N2 atmosphere.
To verify the feasibility of Co-Ru/C for the transfer
hydrogenation reactions,
a series of biomass-derived
compounds containing carbonyl groups were employed as
the feedback. As shown in Table 5, more than 85 %
conversions are achieved over the Co-Ru/C catalyst in all
cases, while the selectivities to target alcohols are above
94 %. This result reflects the excellent catalytic
performance of Co-Ru/C catalyst in the transfer
hydrogenation of carbonyl compounds, which offers the
potential of expanding industrial application in the field of
heterogeneous transfer hydrogenations.
For comparison, NiAlRu-LDH-C, ZnAlRu-LDH-C and
MgAlRu-LDH-C composite precursors were synthesized
according to the same procedure as for CoAlRu-LDH-C in the
Conclusions
In summary, we designed and prepared
presence
of
Ni(NO3)2⋅6H2O,
Zn(NO3)2⋅6H2O
or
a carbon-
Mg(NO3)2⋅6H2O instead of Co(NO3)2⋅6H2O. The corresponding
reduced samples were denoted as Ni-Ru/C, Zn-Ru/C and Mg-
Ru/C, respectively. Moreover, the above obtained CoAlRu-LDH
precursor was immediately heated to 600 °C at a ramping rate
of 5 °C min-1 under N2 atmosphere and held for 3 h to obtain
Co-Ru comparison sample.
supported oxide-modified Co-Ru/C catalyst with a large
number of surface defects (i.e. oxygen vacancies, Co2+
species,) via
a
two-step hybridization-self reduction
approach, which was employed in liquid-phase transfer
hydrogenation of FA using benzyl alcohol as the hydrogen
donor. It was found that almost full conversion with 100 %
selectivity to FOL was achieved in 12 h at 150 °C under
nitrogen atmosphere. A series of characterizations and
experiments revealed that the significantly improved
transfer hydrogenation of FA over the Co-Ru/C catalyst
was associated with strong interactions between Ru
species and Co-containing spinel matrix, thereby
generating a large amount of surface defects. These
surface defects significantly facilitated the chemisorption of
FA, which could spatially construct a channel for the
electron transfer for the activation of carbonyl groups. The
excellent efficiency for transfer hydrogenation of FA can be
impossible to attain by other supported Ru-based catalysts
derived from LDH-C composites. Such flexible, green,
high-efficient carbon-supported Ru-based catalyst system
provides promising potential for the transfer hydrogenation
of carbonyl compounds.
Characterization
Powder X-ray diffraction (XRD) measurements were
performed on
a Shimadzu XRD-6000 diffractometer using
graphite-filtered Cu Kα source (λ= 0.15418 nm) at 40 kV and 30
mA.
Elemental analysis was carried out using a Shimadzu ICPS-
7500 inductively coupled plasma atomic emission spectroscopy
(ICP-AES) after the samples were dissolved in nitrohydrochloric
acid. The carbon content was analyzed by elemental
microanalysis (Elementar Vario analyzer).
Transmission electron microscopy (TEM) and high-
resolution TEM (HRTEM) images were obtained on a JEOL
JEM-2100 high-resolution transmission electron microscope
with the accelerating voltage of 200 kV. The size distributions of
metal NPs were estimated from more than 200 particles, while
the surface area-weighted diameter of particles (D) was
deduced based on the following equation (1):
n d3
(1)
Experimental Section
∑
∑
i
i
i
i
D =
n d2
i
i
Materials
where ni is the number of particles with the diameter of di.
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10.1002/cctc.201601070
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FULL PAPER
High-angle annular dark-field scanning TEM-energy-
dispersive X-ray spectroscopy (HAADF-STEM-EDX) images
were recorded on a JEOL2010F instrument.
self-supporting wafer. The wafer was introduced into evacuable
IR cell with CaF2 windows, evacuated at 200 °C for 2 h under
Ar flow, and then cooled to 30 °C. Afterwards, pyridine was
introduced and balanced for 1 h. Finally, physisorbed pyridine
was removed by evacuation and the spectra were recorded.
Catalytic test
N2 adsorption–desorption isotherms of samples were
obtained on a Micromeritics ASAP 2020 sorptometer apparatus.
The total specific surface areas were determined by the
multipoint Brunauer–Emmett–Teller (BET) method, while the
pore volume and average pore diameter were estimated by the
Barrett–Joyner–Halenda (BJH) method according to desorption
isotherms.
The liquid phase transfer hydrogenation of FA was carried
out in a 100 mL stainless steel autoclave equipped with a
magnetic stirrer. At the beginning of the experiment, FA (0.3
mL, 3.6 mmol), benzyl alcohol (10 mL, 96 mmol), and the
catalyst (0.1 g) were put into the reactor. The air in the reaction
reactor was flushed out using 2.0 MPa N2 at least ten times.
Then, the reactor was submerged into an oil bath under N2
Temperature-programmed reduction (TPR) and hydrogen
temperature-programmed desorption (H2-TPD) measurements
were conducted on a Micromeritics ChemiSorb 2920 with a
thermal conductivity detector (TCD). Before measurements, the
reduced sample (100 mg) was degassed under flowing argon
(40 mL min-1) at 600 °C for 3 h. For TPR, the reduced sample
was further treated in a flow of H2/Ar gas mixture (1:9, v/v; 40
mL min-1) with a heating rate of 10 °C min-1 from 50 °C to
900 °C. For H2-TPD, the reduced sample was treated in a flow
of H2/Ar gas mixture and held for 2 h at 25 °C. At last,
chemisorbed H2 was desorbed in a flow of argon at a ramping
rate of 10°C min-1. Based on the H2 chemisorption capacity, the
apparent dispersion of Ru (Dis, %) was calculated using the
following equation (2):
atmosphere at
a designated temperature and initiated by
stirring with a rate of 900 rpm. After reaction, the autoclave was
cooled with an ice-water bath and depressurized carefully.
Finally, the liquid products were analyzed by an Agilent
GC7890B gas chromatograph equipped with flame ionization
detector and DB-wax capillary column (30.0 m×250μm×0.25
μm) and identified as compared with known standards using
dodecane as an internal standard. In all cases, the carbon
balances were above 96 %. The injector temperature was set
at 250 °C, and the detector column temperature was increased
from 100 to 150 °C with a ramp rate of 5 °C min-1. The
experimental errors for the conversions and selectivities were
−1
cat
H2 uptake/mol g ×SF
(2)
Dis (%) =
×MRu /g mol−1 ×100
less than
3 % obtained according to at least 3 parallel
%w/w Ru×RD
experiments.
where H2 uptake (mol gcat–1) is moles of H2 desorbed per unit
weight of reduced sample, MRu is the formula weight of Ru (MRu
= 101.07 g mol–1), %w/w Ru is the weight percentage of Ru in
sample as determined by ICP-AES, RD (%) is the reduction
degree of samples estimated by XPS of Ru 3d core level, and
SF is the stoichiometric factor (the Ru/H = 1/1) which is taken
as 2.
Acknowledgment
This study was funded through National Natural
Science Foundation of China (21325624; 21521005),
the Beijing Engineering Center for Hierarchical
Catalysts, and Fundamental Research Funds for the
Central Universities (buctrc201528).
Oxygen storage capacity (OSC) of reduced samples was
measured by the oxygen pulse injection method. First, the
sample (100 mg) was purged with a flow of He (40 mL min-1) at
600 °C. Subsequently, a stream of O2/He (1:9, v/v; 40 mL min-1)
was periodically injected into the sample until the signal area
was constant. The amount of oxygen consumption was defined
as OSCcat (mol g-1). Considering that the stoichiometric factor
between Ru0 and oxygen atom is 1:1, the number of surface
oxygen vacancies (Nv) can be calculated using the following
equation (3):
Keywords: Ruthenium • Surface oxygen vacancies •
Promotional effects • Transfer hydrogenation • Furfural.
References
[1] G.H. Wang, J. Hilgert, F. H. Richer, F. Wang, H.J. Bongard, B.
Spliethoff, C. Weidenthaler and F. Schuth, Nature. Mater.,
2014, 13, 293-300.
[2] J. Jae, W. Zheng, A. M. Karim, W. Guo, R. F. Lobo and D. G.
Vlachos, ChemCatChem, 2014, 6, 848-856.
[3] C. Xiao, T.W. Goh, Z. Qi, S. Goes, K. Brashler, C. Perez and
W. Huang, ACS Catal., 2016, 6, 593-599.
Dis×%w / wRu× RD
MRu /g mol−1
(3)
Nv = OSCcat
−
[4] A. Corma, S. lborra and A. Velty, Chem. Rev., 2007, 107,
2411-2502.
[5] M.M. Villaverde, N.M. Bertero, A.J. Marchi and T.F. Garetto,
Catal. Today, 2013, 213, 87–92.
X-ray photoelectron spectroscopy (XPS) was recorded on a
Thermo VG ESCALAB250 X-ray photoelectron spectrometer
using a monochromatic Al Kα X-ray radiation of 1486.6 eV
photons. All binding energy values were calibrated based on
the graphite C1s peak at 284.6 eV.
[6] C. Xu, L. Zheng, D. Deng, J. Liu and S. Liu, Catal. Commun.,
2011, 12, 996–999.
[7] W. Huang, H. Li, B. Zhu, Y. Feng, S. Wang and S. Zhang,
Ultrason. Sonochem., 2007, 14, 67–74.
In situ Fourier transform infrared (FT-IR) spectra of FA
adsorption and were recorded at 30 °C using a Thermo Nicolet
380 FT-IR spectrometer. The sample (30 mg) pressed into a
self-supporting wafer was placed into an evacuable IR cell with
CaF2 windows, and then evacuated at 350 °C for 1 h. After
cooling to 30 °C, FA was introduced and held for 1 h. Finally,
physisorbed FA was removed by evacuation under vacuum.
Surface acidity was determined by IR spectroscopy of
pyridine (Py-IR) adsorbed on catalysts on a Thermo Nicolet
380 spectrometer. The sample (50 mg) was pressed into a
[8] H. Li, H. Luo, L. Zhuang, W. Dao and M. Qiao, J. Mol. Catal., A,
2003, 203, 267–275.
[9] N. Merat, C. Godawa and A. Gaset, J. Chem. Tech.
Biotechnol., 1990, 48, 145–159.
[10] H.Y. Zheng, Y.L. Zhu, B.T. Teng, Z.Q. Bai, C.H. Zhang, H.W.
Xiang and Y.W. Li, J. Mol. Catal., A, 2006, 246, 18–23.
[11] M. Hronec and K. Fulajtarova, Catal. Commun., 2012, 24, 100–
104.
[12] Y. Roman-Leshkov, C. J. Barrett, Z. Y. Liu and J. A. Dumesic,
Nat. Lett., 2007, 47, 982–986.
10
This article is protected by copyright. All rights reserved.

10.1002/cctc.201601070
ChemCatChem
FULL PAPER
[13] S. Sitthisa, T. Pham, T. Prasomsri, T. Sooknoi, R. G. Mallinson
and D. E. Resasco, J. Catal., 2011, 280, 17–27.
[14] D. Scholz, C. Aellig and I. Hermans, ChemSusChem., 2014, 7,
268–275.
[47] S. Ponce, M. A. Peña and J. L. G. Fierro, Appl. Catal., B, 2000,
24, 193–205.
[48] A. A. Dabbawala, D. K. Mishra and J.S. Hwang, Catal. Today,
2016, 265, 163-173.
[15] B.M. Nagaraja, A.H. Padmasri, B. D. Raju and K.S. R. Rao, J.
Mol. Catal., A, 2007, 265, 90–97.
[49] L. He, Z. Li and Z. Zhang, Nanotechnology, 2008, 19, 155606–
155621.
[16] I. Gandarias, S. G. Fernández, M. E. Doukkali, J. Requies and
P. L. Arias, Top Catal., 2013, 56, 995–1007.
[50] V. G. Hadjievl, M. N. Ilievl, I. V. Vergilov, J. Phys. C: Solid
State Phys., 1988, 21, l99-206.
[17] I. Gandarias, J. Requies, P.L. Arias, U. Armbruster and A.
Martin, J. Catal., 2012, 290, 79–89.
[51] Q. Liu, L.C. Wang, M. Chen, Y. Cao, H.Y. He and K.N. Fan, J.
Catal., 2009, 263, 104-113.
[18] B. M. Nagaraja, A. H. Padmasri, B. D. Raju and K. S. R. Rao,
Int. J. Hydrogen Energy, 2011, 36, 3417–3425.
[19] B. M. Nagaraja, A. H. Padmasri, P. Seetharamulu, K. H. P.
Reddy, B. D. Raju and K. S. R. Rao, J. Mol. Catal., A, 2007,
278, 29–37.
[52] I. Lopes, N. E. Hassan, H. Guerba, G. Wallez and A. Davidson,
Chem. Mater., 2006, 18, 5826-5828
[53] B. Mallesham, P. Sudarsanam, G. Raju and B. M. Reddy,
Green Chem., 2013, 15, 478-489.
[54] J. W. Shabaker, R. R. Davda, G. W. Huber, R. D. Cortright and
J. A. Dumesic, J. Catal., 2003, 215, 344–352.
[55] P. Panagiotopoulou, N. Martin and D. G. Vlachos,
ChemSusChem, 2015, 8, 2046-2054.
[20] J. Yang, H.Y. Zheng, Y.L. Zhu, G.W. Zhao, C.H. Zhang, B.T.
Teng, H.W. Xiang and Y. Li, Catal. Commun., 2004, 5, 505–
510.
[21] C. Pramond, M. Suresh, V. Mohan, B. Sridevi, B. David Raju
and K. Rama Rao, J. Chem. Sci., 2014, 126, 311–317.
[22] L. Bui, H. Luo, W. R. Gunther and Y. Román-Leshkov, Angew.
Chem. Int. Ed., 2013, 52, 8022–8025.
[56] J. Li, J. Liu, H. Zhou and Y. Fu, ChemSusChem, 2016, 9, 1339
–1347.
[57] D. Scholz, C. Aellig and I. Hermans, ChemSusChem, 2014, 7,
268 –275.
[23] M. Chia and J. A. Dumesic, Chem. Commun., 2001, 47,
12233–12235.
[58] N. M. Bertero, A. F. Trasarti, C. R. Apesteguía and A. J. Marchi,
Appl. Catal., A, 2011, 394, 228-238.
[24] J. Jae, W. Zheng, R. F. Lobo, D. G. Vlachos, ChemSusChem,
2013, 6, 1158–1162.
[59] A. F. Trasarti, N. M. Bertero, C. R. Apesteguía and A. J. Marchi,
Appl. Catal., A, 2014, 475, 282-291.
[25] R. Han, C. Nan, L. Yang, G. Fan and F. Li, RSC Adv., 2015, 5,
33199–33207
[60] M. M. Villaverde, T. F. Garetto and A.J. Marchi, Catal.
Commun., 2015, 58, 6-10
[26] R. Pestman, R. M. Koster, J. A. Z. Pieterse and V. Ponec, J.
Catal., 1997, 168, 255-264.
[61] From http://webbook.nist.gov/.
[62] L. E. Murillo and J. G. Chen, Surf. Sci., 2008, 602, 919-931.
[63] L.R. Baker, G. Kennedy, M.V. Spronsen, A. Hervier, X. Cai, S.
Chen, L.W. Wang and G.A. Somorjai, J. Am. Chem. Soc., 2012,
134, 14208-14216.
[27] H. G. Manyar, C. Paun, R. Pilus, D. W. Rooney, J. M.
Thompsona and C. Hardacre, Chem. Commun., 2010, 46,
6279–6281.
[28] A. Boffa, C. Lin, A. T. Bell and G. A. Somorjai, J. Catal., 1994,
149, 149–158.
[64] B. Bachiller-Baeza, I. Rodriguez-Ramos and A. Guerrero-Ruiz,
Appl. Catal., A, 2001, 205, 227–237.
[29] Q. Hu, L. Yang, G. Fan and F. Li, J. Catal., 2016, 340, 184–
195.
[65] L. Li, N. Guan, Microporous Mesoporous Mater., 2009, 117,
450-457.
[30] J. Ye, C. Liu, D. Mei and Q. Ge, ACS Catal., 2013, 3, 1296–
1306.
[66] G. Busca, Phys. Chem. Chem. Phys., 1999, 1, 723–736.
[67] H. Yue, Y. Zhao, S. Zhao, B. Wang, X. Ma and J. Gong, Nat.
Commun., 2013, 4, 2339–2346.
[31] Q. Tang, L. Jiang, J. Qi, Q. Jiang, S. Wang and G. Sun, Appl.
Catal., B, 2011, 104, 337–345.
[68] J. Gong, H. Yue, Y. Zhao, S. Zhao, L. Zhao, J. Lv, S. Wang
and X. Ma, J. Am. Chem. Soc., 2012, 134, 13922–13925.
[69] K. Yan, J. Liao, X. Wu and X. Xie, RSC Adv., 2013, 3, 3853–
3856.
[32] F. Li and X. Duan, Struct. Bonding., 2006, 119, 193–223.
[33] G. Fan, F. Li, D. G. Evans and X. Duan, Chem. Soc. Rev.,
2014, 43, 7040–7066.
[34] P. J. Sideris, U. G. Nielsen, Z. H. Gan and C. P. Grey, Science,
2008, 321, 113−115.
[35] J. Wang, G. Fan, F. Li, RSC Adv., 2012, 2, 9976–9985.
[36] W. Li, G. Fan and F. Li, Catal. Sci. Technol., 2016, 6, 2337–
2348.
[37] S. Sankaranarayanan, A. Sharma and K. Srinivasan, Catal. Sci.
Technol., 2015, 5, 1187–1197.
[38] C. Rudolf, B. Dragoi, A. Ungureanu, A. Chirieac, S. Royer, A.
Nastro and E. Dumitriu, Catal. Sci. Technol., 2014, 4, 179–189.
[39] Y. Zhang, D. Wei, S. Hammache and J. G. G. Jr, J. Catal.,
1999, 188, 281–90.
[40] Y. Zhao, J. Zhou, J. Zhang and S. Wang. Catal. Lett., 2009,
131, 597–605.
[41] P. S. S. Reddy, N. Pasha, M. G. V. C. Rao, N. Lingaiah, I.
Suryanarayana and P. S. S. Prasad, Catal. Commun., 2007, 8,
1406–1410.
[42] K. A. Pokrovski and A. T. Bell, J. Catal., 2006, 244, 43–51.
[43] H. Y. Kim, H. M. Lee and G. Henkelman, J. Am. Chem. Soc.,
2012, 134, 1560-1570.
[44] L. F. Liotta, G. D. Carlo, G. Pantaleo, A. M. Venezia and G.
Deganello, Appl. Catal., B, 2006, 66, 217-227.
[45] Y. Feng, L. Li, S. Niu, Y. Qu, Q. Zhang, Y. Li, W. Zhao, H. Li
and J. Shi, Appl. Catal., B, 2012, 111–112, 461–466.
[46] S. Rousseau, S. Loridant, P. Delichere, A. Boreave, J. P.
Deloume and P. Vernoux, Appl. Catal., B, 2009, 88, 438-447.
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10.1002/cctc.201601070
ChemCatChem
Entry for the Table of Contents
FULL PAPER
A new strategy was employed to
construct surface defects on carbon-
supported oxide-modified Ru-based
catalys via a two-step hybridization-
self reduction route, and the as-
fabricated defect-rich Ru-based
catalyst exhibited excellent catalytic
Zhi Gao, Lan Yang, Guoli Fan,
Feng Li*
Page No. – Page No.
Promotional role of surface
defects on carbon supported
Ru-based catalysts in transfer
hydrogenation of furfural
performance
hydrogenation of furfural, mainly due
to the promotional effects of
in
the
transfer
a
quantity of surface defects (oxygen
vacancies, Co2+ species) on the
chemisorption and activation of
furfural molecule.
This article is protected by copyright. All rights reserved.